Export symbols needed by the Chromium component build (part 8).

This CL uses RTC_EXPORT (defined in rtc_base/system/rtc_export.h)
to mark WebRTC symbols as visible from a shared library, this doesn't
mean these symbols are part of the public API (please continue to refer
to [1] for info about what is considered public WebRTC API).

[1] - https://webrtc.googlesource.com/src/+/HEAD/native-api.md

Bug: webrtc:9419
Change-Id: Ib2c29054b2ae008f5291bd3b762a504b18534326
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/130513
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27410}
diff --git a/modules/video_coding/include/video_codec_interface.h b/modules/video_coding/include/video_codec_interface.h
index 1b22cae..e0377ed 100644
--- a/modules/video_coding/include/video_codec_interface.h
+++ b/modules/video_coding/include/video_codec_interface.h
@@ -20,6 +20,7 @@
 #include "common_video/generic_frame_descriptor/generic_frame_info.h"
 #include "modules/include/module_common_types.h"
 #include "modules/video_coding/include/video_error_codes.h"
+#include "rtc_base/system/rtc_export.h"
 
 namespace webrtc {
 
@@ -100,7 +101,7 @@
 // Note: if any pointers are added to this struct or its sub-structs, it
 // must be fitted with a copy-constructor. This is because it is copied
 // in the copy-constructor of VCMEncodedFrame.
-struct CodecSpecificInfo {
+struct RTC_EXPORT CodecSpecificInfo {
   CodecSpecificInfo();
   CodecSpecificInfo(const CodecSpecificInfo&);
   ~CodecSpecificInfo();